OpenEuphoria

Problem with re-creating pixmaps when resizing

• Posted by Alexander Toresson <toressonodakra at swipnet.se> Jun 28, 2004
• 420 views

I'm coding on a program which will resize the view to the size of the
window and at the same time keep the aspect ratio of the view. I'm
double-buffering with a pixmap. The problem is that after I've destroyed
and created the pixmap again, the background of the window will be filled
with garbage! Anyone know why?

Here's a little piece of code to demonstrate:

include win32lib.ew
atom width, height
integer need_repaint
integer xratio, yratio
integer main, pixmap

xratio = 4
yratio = 3

width = 100
height = 100

need_repaint = 1

main = create(Window, "Resize and see the \"effect\"", 0, Default, Default, 640,
480, 0)
pixmap = create(Pixmap, "", 0, 0, 0, width, height, 0)

procedure main_onpaint(integer self, integer event, sequence params)
integer x, y
    if need_repaint then
        setPenColor(pixmap, Black)
        drawRectangle(pixmap, True, 0, 0, width, height)
        setPenColor(pixmap, BrightBlue)
drawRectangle(pixmap, True, floor(0.25 * width), floor(0.25 * height),
        floor(0.75 * width), floor(0.75 * height))
        need_repaint = 0
    end if
    copyBlt(main, 0, 0, pixmap)
end procedure
setHandler(main, w32HPaint, routine_id("main_onpaint"))

procedure main_onresize(integer self, integer event, sequence params)
    destroy(pixmap)
width = params[2]                                     -- window width is
    limiting?
    height = floor((yratio / xratio) * width+.5)
if height > params[3] then                            -- window height is
    limiting!
        height = params[3]
        width = floor((xratio / yratio) * height+.5)
else                                                  -- window width is
    limiting!
    end if
    pixmap = create(Pixmap, "", 0, 0, 0, params[2], params[3], 0)
    need_repaint = 1
    repaintWindow(main)
end procedure
setHandler(main, w32HResize, routine_id("main_onresize"))

WinMain(main, Normal)

Shhh! Be vewy quiet! I'm hunting wuntime ewwows!